Heat transfer unit



Sept. 15, 1959 D. L. CONING HEAT TRANSFER UNIT 2 Sheets-Sheet 1 FiledSept. 26. 1956 INVENTOR.

Donald L. Con/fig BY g His Attorney D. L. CONING HEAT TRANSFER UNITSept. 15, 1959 2,903,863

Fil ed Sept. 26. 1956 2 Sheets-Sheet 2 INVENTOR.

Don a/a' L. Con/n9 BY 6 g 4 His Attorney United Patent 7* i HEATTRANSFER UNIT Donald-1L. Coning, New Lebanon, Ohio, assignor to General'Motors Corporation, Detroit, Mich, acorporation of Delaware ApplicationSeptember 26; 1956, Serial No. 612,247 I 1 Claim. (Cl. 62289) Thisinventionrelates to a refrigerating apparatus and,

more particularly to plate-type evaporators haying liquid catching meansat one edge.

As shown in the Jacobs et a1. Patent 2,672,023 issued March 16, 1954,catch troughsfsuch as the catch trough 7 0' have been provided beneathplate evaporators. Such; troughs are somewhat expensivenotonlybecauseofthe cost of the trough itself but also in the cost; ofassembling it into. the refrigerantfcabinet. Such troughs also reducethe amount of usable space within the; cabinet.

These and-otherobjects are obtained in the form shown,

in the drawings, in which a: plate is bonded together except along oneedge and except where refrigerant passages are desired'by a roll bondingandhydraulic expansion process such as is described'j in the Long.Patent 2,662,273 issued" December 15, 1953. edge is separated by a knifeedge and the two, portions are bent outwardly and upwardly to form theliquid catching groove or trough. For gravity air flow the trough orgroove will normally be placed at the bottom but for forced air flow thetrough or groove may be placed in the trailing edge of the evaporator orheat exchange no matter whether this edge is at the bottom, top, orsides.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Figure 1 is a diagrammatic view of a refrigerator embodying one form ofmy evaporator;

Figure 2 is a plan view of one of the sheet portions of the evaporatorplate after stop weld material has been applied thereto;

Figure 3 is a diagrammatic view in elevation showing another sheetsuperimposed upon the one shown in Figure 2 undergoing roll bonding; 0

Figure 4 is a diagrammatic view in elevation showing the plate afterroll bonding with the one edge split by a knife edge and in the processof having the bifurcations bent through about to form integral troughson either side;

Figure 5 is a front view showing the evaporator plate after thehydraulical expansion of the refrigerant passages;

Figure 6 is an end view of Figure 5;

Figure 7 is a fragmentary front .view showing a spout attached to oneend portion of these troughs;

Figure 8 is an end view of the portion of the evaporator shown in Figure7;

The nongbonded; 40

2,993,863 Patented Sept. 15, 1959 Figure 9 is a modified plan view of asheet portion provided with stop weld material;

Figure 10 is a diagrammatic view in elevation showing another sheetsuperimposed upon the one shown in Figure 9 undergoing the roll bonding;

Figure 11 is a view in elevation diagrammatically showing the method ofslitting the lower edge after the lower edge has been. hydraulicallyexpanded;

' Figure 12 is an end view of Figure 11;

Figure 13 is a fragmentary view illustrating the fiattening of thebifurcations of the lower edge shown in Figures 11 and 12; and

Figure 14 is a view illustrating the bending of the bifurcations shownin Figure 13 into the form of a trough.

Referring. now to Figure 1 there is shown diagrammatically a.refrigerator cabinet 20 having insulated walls enclosing an upperfreezing compartment 22, an above freezing foodstorage compartment '24with an insulated Wall '26vdividing the two compartments. Beneath thefood storage compartment 24 there is also provided a machine compartment28, containing a sealed motor-compressor unit 30 and a condenser 32.The. condenser 32 is connected by a capillary tube 34 to the upperportion of a U -shaped freezing evaporator 36 locatedin the freezingcompartment '22. The opposite upper portion of the evaporator. 36, isconnected by a conduit 38 to the upper rightfcorner of a plate-typeevaporator 40. The evaporatorAll has refrigerant passages 59 formedtherein by the roll bonding Processes illustrated in Figures 2 to 14.The, outlet of, these refrigerant passages is connected by the suctionconduit 42 to the suction entrance of the sealed mqtoncornpressor unit30. The capillary tube 34 and the suction conduit 42 are preferablybonded together to serve as a heat exchanger between the compressedrefrigerant and; the evaporated refrigerant. The refrigerating systempreferably is controlled by a snap acting thermostatic switch 44.connected in series with motor-compressor unit 30 andcontrolled by athermostatic bulb 46 mounted upon the lower portion of evaporator 40.This switch 44 is preferably adjusted to operate on a defrosting cycleso that frost accumulates during the running periods upon the plateevaporator 40 and melts therefrom during the off cycle.

According to this invention to catch condensate or frost meltingtherefrom, the plate evaporator 40 is provided with integral liquidcatching troughs 48 which are formed from the bifurcations extendingalong the bottom edge of the evaporator 40. The bifurcations extend inopposite directions outwardly and upwardly into the form of a hook shapeto serve as troughs or other forms of liquid catching devices. To oneend of these troughs is attached a spout 50 which discharges into thedrain tube 52 extending into the machine compartment 28 for dischargingmelted frost into an open-topped receptacle provided upon the top of thesealed motor-compressor unit 30. Either the entire plate 40 or thetroughs 48 alone are preferably provided with a slight slant or falltoward the spout 50 to assist in the gravity flow of the collectedliquid to the spout. This moisture is heated in the receptacle 54 bywaste heat dissipated by the motor-compressor unit 30 and caused toevaporate.

The plate type evaporator 40 is preferably formed by the roll bondingprocess described in the aforementioned Long Patent 2,662,273 issuedDecember 15, 1953. In

5 this roll bonding process, stop weld material is applied which havebeen applied by the roll bonding process illustrated in Figure 3 anddescribed in further detail in the aforementioned Patent 2,662,273.After the roll bonding has taken place producing a forge weld betweensheets except where the stop weld material is applied, the one edge ofthe bonded plate is separated by a knife edge 64 in the vicinity of thestop weld material 60. This is permitted by the stop weld material 60which slit by forcing it onto a cutting or splitting tool or knifeseparates the bifurcations 66 and 68. Two removable metal rods 70 and 72are provided adjacent each other just above the knife edge 64. These arelocated on opposite sides of the forge weld sheets 56 and 62. The stopwelded sheets are bent approximately 180 in either direction over eitherof the rods 70 and 72 to form the drain troughs with the other rod beingtemporarily removed. After this, the sheets may be hydraulicallyseparated and expanded in the area of the stop weld material 58 betweenflat dies in the manner shown in the aforementioned Long Patent2,662,273 to form a continuous passage 59. Then the upper edge may betrimmed exposing both ends of the passage 59 formed in this manner.

The upper edge may be trimmed to complete the plate evaporator 40 properas shown in Figures 1, 5 and 6. After this, there is attached a shortsheet metal spout 50 which envelops one end of the troughs and has upperinwardly turned supporting edges 76 and 78 which book over the edges ofthe troughs 80 and 82.

Liquid catching in the troughs 48 flows from the spoutv 50 into thedrain tube 52 which discharges the moisture into the receptacle 54 inthe machine compartment 28.

In Figures 9 to 14, a modified form of the invention is shown in whichthe sheet 156 has a stop weld material 158 to form a refrigerant passage159 similar to.

the refrigerant passage 59 for the plate evaporator 56. However, stopweld material 160 instead of being applied to and including the loweredge is spaced from the lower edge as shown in Figure 9. Another sheetportion is superimposed upon the sheet portion 156 and the two are rollbonded together as shown in Figure 10. The lower edge becomes bondedtogether. The portions between the sheets containing the stop weldmaterial are hydraulically expanded. This forms a tubular shape adjacent the lower edge of the sheet 156 as shown in Figures 11 to 14. Thisis hydraulically expanded into a tubular shape 148. Thereafter thislower tubular edge 148 is 149 as illustrated in Figures 11 and 12. Thelower edge of the plate is then forced over another knife 164.

The tubular portion is then flattened onto the knife edge 164 by thesqueezing elements onto the sides of the knife edge 164. The plateevaporator 140 is then placed in a tool having the knife edge 64 and theremovable rods 70 and 72 as shown in Figure 4. Then the plate 140 isbent approximately over either of the rods 70 and 72 in oppositedirections to form oppositely extending lower troughs 148. During thisbending the alternate rod is removed. These troughs may be used eitherwhen the evaporators 40 or 140 are operated on a defrost cycle oroperated at above freezing temperatures. The method of manufacture isinexpensive and provides a compact integral trough on either side of thelower edge of the plate. The melted frost flows readily through thetroughs and the spout 50 into the tube 52.

When the plate evaporators 40 or 140 are placed in a forced air streamthe troughs 48 or 148 are positioned at the trailing edge no matter whatthe direction of flow.

While the form of embodiment of the invention asi herein disclosedconstitutes a preferred form, it is to bel understood that other formsmight be adopted, as may come within the scope of the claim whichfollows.

What is claimed is as follows:

A heat transfer unit including an upright metal plate composed of twometal sheet portions bonded together in some areas to form a unitaryplate and separated in other areas to form a fluid passage, the sheetportions at one edge of said plate being separated and extending in ahook shape away from each to form liquid catching surfaces protrudingfrom opposite sides of said plate, and a spout including a U shapedportion having upper turned in portions extending over and engaging theouter I edges of the hook shaped extensions.

References Cited in the file of this patent UNITED STATES PATENTS

